Smaller, transportable nuclear reactor

FILE - In this Saturday, July. 23, 2011 file photo, the No. 3 reactor, right, of the Ikata nuclear power plant, operated by Shikoku Electric Power Co., is seen in Ikata, western Japan. Japan's nuclear watchdog has formally approved new safety requirements for atomic plants, paving the way for the reopening of facilities shut down since the Fukushima disaster. The new requirements approved Wednesday, July 19, 2013, by the Nuclear Regulation Authority will take effect on July 8, when operators wil
— AP

FILE - In this Saturday, July. 23, 2011 file photo, the No. 3 reactor, right, of the Ikata nuclear power plant, operated by Shikoku Electric Power Co., is seen in Ikata, western Japan. Japan's nuclear watchdog has formally approved new safety requirements for atomic plants, paving the way for the reopening of facilities shut down since the Fukushima disaster. The new requirements approved Wednesday, July 19, 2013, by the Nuclear Regulation Authority will take effect on July 8, when operators wil
/ AP

Imagine a nuclear reactor the size of a school bus, built on an assembly line and delivered to operators on a flatbed truck.

This is General Atomics’ vision of a safer, more efficient fission machine that could go 30 years without refueling and reduce daunting startup and equipment costs that have plagued plants like the San Onofre Nuclear Generating Station.

G.A., as it’s known in the business, believes it can deliver such a reactor and is jockeying to win some of the $452 million in development money being handed out by the U.S. Department of Energy.

Getting there would mean prying a raft of researchers and safety regulators away from a lifetime of work refining the dominant nuclear technology, water-cooled reactors that use steam to drive turbines and generate electricity.

“There are times in human history where technologies come along that have the potential of changing the game,” says John Parmentola, senior vice president at G.A.’s Energy and Advance Concepts Group. “The Department of Energy has a choice: It can either continue to fund technology that hasn’t changed very much in 50 years or it can take a bold step to a possible new path to nuclear energy. That is a major decision point.”

Industry insiders already have high hopes for smaller, more foolproof reactors that could be mass produced and cheaply installed.

Climate-change concerns are providing new impetus to make emissions-free nuclear plants more viable, despite problems with storing nuclear waste.

China, where 28 nuclear plants are under construction, is moving from imported nuclear engineering to home-grown technology.

The new General Atomics entry, dubbed the Energy Multiplier Module or “EM²,” sets out to shrink the reactor vessel to a 35-foot tall cylinder, weighing 530 tons, that would be stowed underground.

EM² would operate at 850 degrees Celsius, more than twice the temperature of typical water-cooled reactors that make up the U.S. fleet.

That fast-neutron configuration can squeeze vastly more energy from the fuel supply.

The core would be cooled by helium, with the inert gas flowing through adjacent turbines to make electricity.

That eliminates the complex steam works associated with water-cooled plants. Gone too are massive heat exchangers like the generators linked to the San Onofre Nuclear Generating Station’s early retirement in June.

Each reactor could power a city of 330,000.

“This is very simple,” says Parmentola, front man for the General Atomics proposal. “I go from the heated medium and drive a turbine, directly. That’s the most efficient way of doing it.”

Above all, he said, the design is geared toward making cost-competitive electricity in an age of abundant natural gas.

In the early decades of nuclear power, water-cooled reactors quickly grew beyond a gigawatt in size — powering more than a million homes each — to achieve new economies of scale.

That paradigm is on trial in Georgia and South Carolina with the construction of four large reactors — the first built in the U.S. in 30 years.

Up-front capital costs — the budget for two reactors at the Vogtle site in Georgia exceeds $14 billion — have become an obstacle for utilities in the U.S. and all but the largest foreign government-backed enterprises.

“The point of the small modular reactor is it’s a much smaller bite ... both financially and physically,” explains Jacopo Buongiorno, a nuclear science and engineering professor at the Massachusetts Institute of Technology. “It’s now smaller by an order of magnitude. It’s a lot easier for a utility to start a project. Even if the project goes bad, for whatever reason, it’s not going to bankrupt the company.”

Smaller reactors allow for more “passive” safety features that use natural properties — gravity, buoyancy, thermal circulation and heat conduction — to maintain cooling and other systems without backup electricity.

Those features have gained favor since the 2011 Fukushima Daiichi plant meltdown in Japan, in which backup generators were swamped by a giant tsunami.

The downsized nuclear race is playing out among the world’s premier builders and vendors.

A first round of federal funding was assigned in November to a modified light-water reactor design. The “mPower” project comes from Babcock and Wilcox of Charlotte, N.C., and Bechtel of San Francisco — builder of San Onofre — with purchase commitments from the Tennessee Valley Authority.

For the General Atomics proposal, much of the underlying technology remains unproven.

The privately held company, a pioneer in several fields of nuclear research, is refining materials that can stand up to intense heat and bombardment by fast neutrons at the core of its EM² reactor.

One key component is a silicon carbide tube, or “cladding,” that supports small pucks of uranium without absorbing neutrons. The metal cladding in traditional commercial reactors — a Zirconium alloy — won’t hold up.

The effort taps materials research conducted at the Idaho National Laboratory. General Atomics has teamed up with construction conglomerate Chicago Bridge & Iron and Mitsubishi Heavy Industries, which has experience with fast reactor construction and gas-cooled reactors in Japan. (Mitsubishi manufactured faulty replacement steam generators linked to the San Onofre shutdown.)

The project’s most daunting hurdle: passing muster at the Nuclear Regulatory Commission.

The agency licensed a high-temperature, gas-cooled reactor built by General Atomics once before at Fort St. Vrain in Colorado. The utility-owned plant was plagued by mechanical issues and retired a generation ago.

General Atomics contends the EM², under a loss of coolant and power, winds down by itself to safe temperatures.

Prominent voices urging the U.S. to nurture fast-neutron reactors include British entrepreneur Richard Branson and Microsoft founder Bill Gates.

Gates is one backer of an entirely private-funded effort by Bellevue, Wash.-based TerraPower for a large-scale traveling wave reactor, a distinctive fast-neutron configuration that burns slowly across a dense fuel core.

The U.S. is brimming with interest in innovative reactors, says Ashley Finan, manager of the Energy Innovation Project at the Clean Air Task Force in Boston, says.

“I think we have the most entrepreneurs in the space, but they’re just unable to move forward,” she says.

The rigor of the U.S. reactor licensing process has made it the preferred route for winning acceptance worldwide. But analysts say that’s unlikely to hold back other countries from bringing their own designs to market.

“We can lose influence on international policies.” Finan says. “If we lose that, it’s arguably going to be China or Russia that are going to wind up with the most influence.”